[DOCS] Update resource civo_kubernetes_cluster documentation example

[AOrps]

Description

1. Make saving kubeconfig to state optional for civo_kubernetes resource #309 Introduced a change that prevented writing the kubeconfig to the state. However the docs aren't updated to keep this in mind. The Documentation improvement, I am suggesting is to simply add a write_kubeconfig = true line to the hcl file.

Current Docs look like this:

And can be found here: https://registry.terraform.io/providers/civo/civo/latest/docs/resources/kubernetes_cluster

edit: looks like some progress was done on this here: #321 so using this one #344 as an extension of it

Acceptance Criteria

Acceptance Criteria

• Add line to hcl docs

write_kubeconfig = true

to https://github.com/civo/terraform-provider-civo/blob/d47a094ca3d5d49938ba030d6e12cef3b3a4725f/docs/resources/kubernetes_cluster.md